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The Asus Zenbook was one of the first entrants in the new ultrabook category when it launched in late 2011. We liked that original system, despite a few serious flaws, and the all-metal design marked it as a direct competitor to the MacBook Air.

Since then, ultrabooks have become both more common and less expensive. Asus now makes several UX variations, including three that we are reviewing, the UX31A, UX32A, and UX32VD. For $1,079, the Zenbook UX31A is neither the most nor least expensive of the current crop, but it is slightly thinner than the other two models.

For three systems that look so similar, there are a lot of differences between them. The 13-inch Asus Zenbook UX32VD comes alluringly close to being an ultrabook without compromise. For $1,299 it includes an Intel Core i7 CPU, a full HD 1,920x1,080-pixel-resolution display, and a discrete Nvida 620M GPU.

The UX32A still has a previous-generation Intel Core i3 CPU. That generation of chip is known by the code name Sandy Bridge, while the latest generation is Ivy Bridge. The Zenbook with the older CPU is slower, and also loses out on new Intel improvements, most notably the new HD 4000 integrated graphics.

Falling between those two extremes is this system, the UX31A. It's a more upscale design variant with a thinner chassis. It skips the GPU of the thicker UX32VD, but keeps the high-res screen and Ivy Bridge internal hardware. But at about $1,079, it doesn't make the most compelling value case. Many ultrabooks with Ivy Bridge components and solid-state drive (SSD) storage are available for around $800 or $900, and the UX31A does nothing in particular to justify a $200-$300 premium. That said, it's still one of the nicer-looking ultrabooks around.

The Zenbook line launched in late 2011 and its design -- aluminum, tapered, and minimalist -- made it the most Air-like of the early ultrabooks, at least until the Dell XPS 13 came around. But it also had a few design miscues. The lid on the original Zenbook was notoriously hard to open. That's been fixed here, across all three new Zenbook models we've reviewed.

The UX31A shares the more tapered design of the original Zenbook. It's slightly thinner and lighter than the UX32A and UX32VD models, although all three have a sharp front lip that can be murder on the heels of your hands, depending on your typing style. Despite the similarities, the small difference in thickness and weight in the UX31A actually feels pretty significant in the hand -- this is the closest to the ultrabook ideal.

The keyboard was a weak point on the original Zenbook, with shallow, clacky keys. The UX31A, with the same thin body, has similar shallow keys. For a better typing experience, check out the other two slightly thicker and heavier Zenbooks. The extra depth on those lets the keyboard have a little more space. Even though the keys here are shallow (a problem on other thin ultrabooks, such as the Sony Vaio T), the keyboard is thankfully backlit, a must-have feature on any ultrabook.

The large but finicky clickpad on the first UX31 was one of our main problems. Thanks to updated driver software from Asus, this feels like a reasonable improvement. It still gets a bit jumpy sometimes, and is under-responsive at other times.

There is, however, a decent set of multitouch gestures, demoed and controlled by the Asus Smart Gesture software app. It's nowhere near as intuitive or responsive as a MacBook trackpad, but that's a Windows-wide problem. One nice touch -- you can set a two-finger tap to indicate a right-click, a very Mac-like move that I've seen popping up a few Windows laptops lately.

In another change from the previous generation of Zenbook laptops, the display is now full HD, with a 1,920x1,080-pixel native resolution. That will be a major selling point to some for playing 1080p video content, but it can make text very small and hard to read at times. The UX32VD model also has a 1080p screen, while the less expensive UX32A has a 1,366x768-pixel screen.

Audio through a speaker grille at the very top of the keyboard tray was predictably thin, despite the Bang & Olufsen ICE Power branding. Audio volume controls are mapped to alternate F-key functions, so you'll need to hit, for example, Fn+F10 to mute the sound.

Compared with the thicker UX32 model Zenbooks, you lose a USB port here, but little else, even with the thinner body. The USB 3.0 ports even charge devices (like phones and media players) while the system is asleep or off.

About The Author

Dan Ackerman leads CNET's coverage of laptops, desktops, and Windows tablets, while also writing about games, gadgets, and other topics. A former radio DJ and member of Mensa, he's written about music and technology for more than 15 years, appearing in publications including Spin, Blender, and Men's Journal.